1. Field of the invention
The present invention is generally concerned with clutches, for automobile vehicles in particular, and is more particularly directed to the assembly of parts, commonly called the clutch cover assembly, to be mounted on a reaction plate or flywheel with a friction disk inserted between them in order to constitute a clutch of this kind.
2. Description of the prior art
Generally speaking, a clutch cover assembly of this kind comprises a first annular part, called the cover, through the intermediary of which it is adapted to be attached to the reaction plate or flywheel to be equipped, a second annular part, called the pressure plate, which is mounted so as to be axially mobile relative to the cover whilst being rotationally coupled to the latter, and axially acting elastic means which, bearing on said cover, continuously urge the pressure plate away from the latter, in order to clamp up the friction disk present between the pressure plate and the reaction plate.
More often than not the cover is of unitary construction, being formed in one piece from a sheet metal blank appropriately cut out and stamped.
It features, disposed at respective ends of an axial part or skirt, on the one hand a first transverse part or rim which is directed radially away from the axis of the assembly and through the intermediary of which it is adapted to bear on the reaction plate to be equipped and, on the other hand, a second transverse part or back which is radially directed towards said axis and through the intermediary of which it is adapted to provide a bearing support for the associated axially acting elastic means.
More often than not the radial extent of this back, the central opening in which defines the internal periphery of the cover, is relatively small, in particular in the case of so-called "pull" type clutches, in which the axially acting elastic means bear on a back of this kind in the immediate vicinity of the axial part or skirt which flanks the latter.
As a result, when a cover of this kind is cut out there is a non-negligible central waste part which may amount to more than half the total weight and which, since more often than not it is not easily recoverable for use, significantly adds to the cost of the assembly.
To minimize this disadvantage it is proposed in U.S. Pat. No. 2,248,378 to divide the cover circumferentially into distinct sectors.
However, failing further provisions, an arrangement of this kind implies that these sectors must be individually attached to the reaction plate to be equipped and therefore that it is necessary to assemble the clutch cover assembly on the reaction plate, without it being possible to assemble the clutch cover assembly as a unit beforehand, which complicates the operation and which is incompatible with at least certain applications in which the reaction plate on the one hand and the clutch cover assembly on the other hand originate from different manufacturers.
In French patent application No. 78 05218 filed Feb. 23, 1978 and published under the No. 2 381 938, there is proposed a structure in which the transverse part forming the back of the cover is subdivided into distinct sectors, the associated axial part resulting from the circular closure upon itself of a strip of sheet metal in one piece.
An arrangement of this kind, by attaching to this axial part the sectors designed to form a back, provides for a unitary cover construction and enables a clutch cover assembly to be produced as a unit which can be handled in isolation before it is mounted on a reaction plate.
However, it does not draw maximum benefit from the subdivision adopted, since this affects only part of the cover.
Furthermore, in both cases there is in service no link between the sectors concerned other than that established between other component parts of the clutch of which it constitutes part.
In other words, in both cases, there is no circumferential continuity between these sectors in service.
Given the moment arm which exists between, on the one hand, the point at which they bear on the reaction plate and, on the other hand, the point at which the associated axially acting elastic means bear on them, they may be subject to distortion which, tending to move them away from the axis of the assembly, is prejudicial to the correct operation of the latter.
A general object of the present invention is an arrangement providing a very simple way of avoiding this disadvantage, combining the advantages of a saving in materials with those of unitary construction, and also conferring further advantages.